Embossed paper toweling and method of production

ABSTRACT

Absorbent paper sheets in multi-ply web form in which the outer webs of the sheet are creped and consist of a series of ribs and grooves. The webs have their ribs secured together by adhesive dispersed in a pattern consisting of individual adhesive zones. The adhesive zones are obtained by providing in embossing apparatus cooperable rolls each having alternating ribs and grooves, the ribs of one roll being provided with protuberances and the other with recesses. The protuberances cover a relatively small area of the total rib area and carry a web on the protuberances through an adhesive applicator so that a relatively small area of the web receives adhesive for attachment to a second web.

[ 1 Feb. 25, 1975 United States tent 1 Thomas 3,571,852 3/1971Gilbert................;............... 425/369 3,756,884 9/1973Hagino;..........,.................... 156/471 1 1 EMBOSSED PAPERTOWELING AND METHOD OF PRODUCTION [75] Inventor: Gordon D. Thomas,Neenah, Wis. Primary Examiner George Lesmes Kimberly-Clark Corporation,Neenah, Wis.

Mar. 15, 1973 [73] Assignee:

Corporation 22] Filed:

[57] ABSTRACT Absorbent paper sheets in multi-ply web form in Appl. No.:341,464

which the outer webs of the sheet are creped and consist of a series ofribs and grooves. The webs have their ribs secured together by adhesivedispersed in a pattern consisting of individual adhesive zones. Theadhesive zones are obtained by providing in embossing apparatuscooperable rolls each having alternating ribs and grooves, the ribs ofone roll being provided with protuberances and the other with recesses.The protu- [56] References Cited berance; cover a retlativetlly smaltllarea of Ill; total1 rib area an carryawe on e pro u erances roug anUNITED STATES PATENTS adhesive applicator so that a relatively smallarea of the web receives adhesive for attachment to a second 161/148Chavannes.......................,.. 161/127Moone................................ Leonard, Jr.

.h C u S 3446 3366 9999 1111 8497. 3569 73 00 v .3 4404 2550 31 5Claims, 16 Drawing Figures 3.868.205 SHEET :1 OF 10 PATENTEB FEB 2 51975III/III!) PATENTED FEBZSIPJS 3' 868 I205 sum c 3 1F 10 FIG. 3

PATENTED #5 SHEET USOF 10 ADHESIVE PATTERN ADHESIVE PATTERN FIG. 8

FIG. 7

FIG. 6

PATENTEU 3,868,205 SHEET UEUF 10 FIG. 9

PATENTED FEB 2 5 SHEET [UN 10 PATENTED F552 5 SHEET U80F 10 w 0 E ZEPEQM2812 SHEET user 10 3'868205 PATH-HEB FEB251975 SHEET IOUF 10 P/JENTEDF552 5 E 75 EMBOSSED PAPER TOWELING AND METHOD OF PRODUCTION BACKGROUNDOF THE INVENTION This invention relates to multi-ply absorbent, softpaper products useful as towels, napkins, wipes and the like. Theinvention is also concerned with methods and apparatus for attainingsuch absorbent paper products utilizing an efficient, suitable andgenerally minimal amount of adhesive to secure attachment of crepedtissue webs to form a multi-ply sheet product.

It is known to provide embossed webs and to laminate them into the formof a sheet by adhesive attachment on a commercial basis. This may bedone by any of several methods. One common method is to apply adhesiveto the embossment surfaces of one of the webs of a sheet product anduniting at the embossment surfaces of the other web. In this instancefor a two-ply web, each web is separately embossed and remains incontact with their respective separate embossing rolls. Adhesive isapplied in a thin layer to the embossment surfaces of one of the webswith commercially available adhesive applicating equipment and both websare joined at their embossment surfaces in the nip formed by the matedsteel embossing rolls. This method provides a high bulk product havinggood quality ply attachment and works satisfactorily with discrete pegtypes of embossing patterns. With other types of embossing patterns,particularly gross patterns consisting of continuous line or embossedline patterns, this method results in application of adhesive to theentire land area of the sheet embossments, even though adhesiveattachment may be obtained at a small portion of the total embossed landarea, by utilizing for embossing, roll patterns which are in crossingrelationship. The result is the use of more total adhesive thannecessary for ply attachment purposes, which increases the product costand also stiffens the product structure.

The present invention is an improvement on prior art practices in thatadhesive is applied in well spaced adhesive zones, and the adhesivezones define embossments which are superposed on more gross embossmentsof the web product. This is accomplished by securing the webs togetherin a combining nip formed by a pair of cooperable embossing rolls havingparticular characteristics. The embossing rolls for the purpose eachhave a series of alternating ribs and grooves disposed about itsperiphery; the ribs of one roll have land areas and projectionsextending above the land areas separated by the land areas, and the ribsof the other roll have land areas and recesses lying below and separatedby these last mentioned land areas of the second roll. The projectionsof one roll in the rotation of the rolls is receivable in matingrecesses of the other said roll. In a further embodiment each of therolls may have projections which cooperate with the recesses of theother roll.

The projections of the embossing roll support a web for the receipt ofadhesive only in the zone of the projection. Since such projections maybe conveniently formed by etching, grinding or the like to a very smallsize. the adhesive application in an adhesive zone may be quite readilylimited. Such leads to good flexibility in the webs and final sheet andis conserving of adhesive.

Another advantage for the above embossing and combining method is thatit results in a product having tractiveness because of the gross natureof the embossments. By providing the continuous lines embossments of oneweb with spaced projections and the other with spaced recesses, a moretextured or woven type appearance is obtained in the product. Thelaminated product still has the same general appearance on both sides.However, the embossment line recesses on one of the webs prior tolamination become slightly raised projections as received in thefinished product. Similarly, the embossment line raised projections ofthe other web become slight recesses after lamination in the finishedproduct. These projections and recesses being confined to the continuousline embossments area tend to break up the continuity of the embossmentsand result in a more pleasing pattern appearance. In fact, the productattains somewhat of a woven fabric appearance.

The invention will be more fully understood by reference to thefollowing detailed description and accompanying drawings wherein:

FIG. 1 is an enlarged and fragmentary view in side elevationillustrating the relationship of the combining rolls of the apparatuswith the creped tissue sheets of the sheet material at the combiningnip;

FIG. 2 is a fragmentary view in perspective of the combining rolls onlyillustrating the cooperative relationship of the spirally contouredrolls and their male and female segments;

FIG. 3 is a view in side elevation of embossing apparatus useful in theproduction of a preferred embodiment of the sheet material andillustrating particularly a four-roll stack having rolls similar tothose illustrated in FIGS. 1 and 2;

FIGS. 4 and 5 are respectively fragmentary views on a somewhat enlargedscale of the combining rolls of FIG. 3;

FIG. 6 is a perspective view of the sheet material with the upper webstripped back from the lower web to reveal the adhesive pattern of thesheet;

FIGS. 7 and 8 are views schematically illustrating useful adhesivepatterns in the practice of the invention, the view in FIG. 7 beingsimilar to that of the structure shown in FIG. 6;

FIG. 9 is a view similar to that of FIG. 3 but illustrating a rollarrangement for the production of a three-ply sheet product;

FIGS. 10 and 11 are respectively enlarged fragmentary views of the upperand lower combining rolls of the structure of FIG. 9;

FIG. 12 is a view in perspective of a three-ply sheet (with the arrowindicating the direction of travel to the product through the combiningrolls of FIG. 9) having the upper and central plies-partially turnedback to reveal the adhesive patterns;

FIG. 13 is a schematic view in plan illustrating more specifically theadhesive patterns of the structure of FIG. 12;

FIGS. 14 and 15 are fragmentary views of a further embodiment of theinvention illustrating cooperating upper and lower combining rollshaving a different form of mating segments; and

FIG. 16 is a fragmentary view in section of a product passing throughthe type of combining rolls illustrated in FIGS. 14 and 15.

Referring now more in detail to the drawings, the numeral (FIGS. 1-3inclusive) designates an upper metallic combining roll which cooperateswith a similar lower metallic combining roll 11. The composite sheetwhich issues from the nip between the combining rolls 10,11 is formed ofan upper creped paper tissue web 12 and a lower creped paper tissue web13. The upper web 12, as it approaches the nip between the combiningrolls, is provided with an adhesive pattern as is most clearly indicatedat 14 in FIGS. 1 and 6.

The upper combining roll 10 is provided with spirally extending ribs 15(FIG. 2) spaced apart by grooves 16. The ribs 15 are generallyrectangular in cross-section, extend at 45 to the direction of sheettravel through the rolls 10,1 1, and are provided over their length witha series of protuberances 17 which extend above land areas 18 separatingthe protuberances. The protuberances 17, as is most clearly shown inFIGS. 2 and 4, have a generally rectangular configuration as viewed inplan except at the roll ends where the protuberances terminate the rolland have a triangular configuration as indicated at 17a. The land areas18 are of greater length in the embodiment illustrated than theprojections 17.

The lower combining roll 11 has ribs 19 which are generally rectangularin cross-section and separated by grooves 20 (FIG. 5). The ribs 19 overtheir length are provided with a series of recesses 21 also rectangularas viewed in plan spaced apart by land areas 22 of greater length thanthe recesses. The ribs 19 extend also at 45 to the direction of sheettravel. The roll ends, as indicated in FIG. 2, are terminated in thearea of the ribs 19 by recessed portions of triangular shape 21a.

The rolls 10,11 rotate in the direction indicated by the arrows (FIG.2). The ribs 15,19 extend transversely to each other and. suitably, theribs have a width of between about 0.015 and 0.050 inch. The grooves 16and 20 preferably have a somewhat greater length in a directionperpendicular to adjacent ribs and are of about 0.015 to about 0.125inch. The ribs, while generally rectangular in cross-section, suitablyhave slightly angled sides to facilitate web movement into the grooves.

Referring now particularly to FIGS. 4 and 5, the projections 17 aredesigned in the operation of the rolls in the manner illustrated in FIG.3 to enter into the'recesses 21. The recesses are specifically madequite shallow to minimize distortion at the recess edges of webs forcedinto the recesses by the action of the projections 17. The projectionsand recesses need, for example, be only about 0.005 inch. Two plies ofthe web material each of thickness of about 0.001 inch are slightlycompressed by the action of the combining rolls in the mannerillustrated in FIG. 1 to insure of good adhesive contact of the webs12,13.

As will be clear from a consideration of FIGS. 4 and 5, the protuberanceb of roll 10, for example, mates with the recess b of roll 11;similarly, the triangular protuberance c cooperates withthe triangularrecess 0.

The webs 12,13 (FIG. 3) are directed to the combining rolls 10,11respectively over rolls 23,24. In the formation of a two-ply sheet theadhesive is applied to the upper traveling web 12 as illustrated in FIG.3. The liquid adhesive material designated at 25 is fed by a fountainroll 26 to a metering roll 27 in thin film form and transferred to roll28. The roll 28 engages the traveling web on the combining roll 10 onlyat the protuberances 17,17a so that only a minor area of adhesiverelative to the web area is added to the traveling web 12 (FIG. 6). Thepattern of the adhesive in a preferred embodiment is clearly shown inFIG. 6. The lower web 13 in FIG. 6 also shows the presence of adhesivein the stripped back zone for the reason that some adhesive will adhereto the lower ply 13 when the strip back action is effected. Mostimportantly, however, the adhesive is only applied in well spaced areaswhere pressure application by the protuberances 17 on material in the recess 21 is effected and all adhesive employed serves in a bondingaction.

Essentially as illustrated in FIG. 7, the sheet may have an area ofabout 9 percent of the total to which adhesive has been applied. If amore flexible sheet is desired, the adhesive may be reduced and FIG. 8illustrates a pattern which is generally sinusoidal and suitable forthis latter purpose. The adhesive is shown at the cross-over points ofthe sinusoidal embossments of overlying webs. In the arrangement of FIG.8 the area having adhesive is about 4 percent of the total area of onesheet.

In order to produce a three-ply product, it is desirable to apply theadhesive to each of the outer plies of the three-ply web in much thesame manner as adhesive has been described as applied to the two-ply webof FIG. 6. Thus, as illustrated in FIG. 9, the creped paper web 13'which is combined at the nip between rolls l0 and 11' with the crepedpaper web 12' is itself adhesively treated. For this purpose aflexographic adhesive printer similar to that described in connectionwith FIG. 3 is provided; this mechanism includes the pond of adhesive25', fountain roll 26', metering roll 27, and transfer roll 28. Themiddle ply of the three-ply web product is indicated at 30 (FIG. 9) andreceives adhesive from each of the outer plies as may be clearly seenfrom FIG. 12. This middle ply may be a strengthening web such as ascrim, an uncreped web or a creped web similar to the outer webs.

The adhesive pattern of the structure of FIG. 12 is, however, quitedifferent than that previously mentioned in connection with FIGS. 6through 8. The different adhesive pattern is obtained by the provisionof engraved'rolls such as indicated in FIGS. 10 and 11. The roll 10 hasa series of spirally extending lands and grooves and the lands areconfigurated as follows. The land portion designated by each numeral 31provides projections similar to those mentioned in connection with roll10. An end projection of triangular form is shown at 31a. Eachprojection 31 lies adjacent a planar portion 32 of the land and a recess33 of a land also lies adjacent each land portion 32. In the upper roll10, then, each land has three levels. Thus, each projection 31 of a landis bounded by a planar portion of the land and each recess is alsobounded by a planar portion of a land except at roll ends; theprojection and recesses at the roll ends alternate around the rollperiphery.

The lower roll 11 (FIG. 11) is provided with lands which have eitherrecesses or projections. The numeral 34 designates the land areas ofeach rib. The recesses from the level 34 are designated at 35 and 35awhile projections from level 34 are indicated at 36 and 36a. As isclearly seen from the drawings, the projections of roll 10' cooperatewith the recesses of roll 11' in a manner similar to that described inconnection with FIGS. 4 and 5. The recess at f, for example, cooperateswith the projection f of roll 11'. By this arrangement the projectionsof roll and the projections 36 of roll 11' receive the adhesive as thesheet 12 and 13' travel to the combining nip (FIG. 9). Much lessadhesive is required while yet permitting the attainment of well adheredplies. The adhesive pattern as applied to the upper sheet 12' isillustrated at 40 (FIG. 12) and that retained by the middle ply uponseparation is indicated at 40. Similarly, the adhesive zone applied tothe lower ply 13 is indicated at 41 and that retained by the middle plyon separation is illustrated at 41'.

FIG. 13 schematically sets forth the adhesive arrangement for a ply ofthe structure of FIG. 12 and, as is clearly shown, each outer sheet hasadhesive on it to the extent of about only 4 5 percent of its surfacearea.

A further embodiment of the invention is illustrated by the FIGS. 14through 16 inclusive. The numeral 42 (FIG. 14) designates an uppercombining roll of a pair, the lower roll being indicated by the numeral43. The upper roll has a series of ribs 44 separated by grooves 45 whilethe lower roll has a series of ribs 46 separated by grooves 47.Projections 48, generally conical in shape, well spaced along the lengthof the ribs 44, mate with generally conical depressions 49 spaced alongthe length of the ribs 46. As will be obvious from the foregoing, thefunction of the projections 48 in the furnishing of a two-ply sheet isto support the upper web as it receives the adhesive in the formingofthe two-ply structure in the same manner as has been described inconnection with FIGS. 1 through 7. However, in this instance theindividual adhesive zones may be small in diameter though preferably therecesses or depressions 49 should be maintained shallow to avoid webdistortion in the adhesive areas.

Very pertinent to the practice of this invention is the saving inadhesive which makes for an economical product. Further. the fact thatmuch of the area of the sheets does not require adhesive provides forminimal stiffness of the product. Additionally, the adhesive zones maybe spaced well apart on any given land area of the product.

EXAMPLE 1 A toweling material was produced by directing base webs to theequipment arrangement of FIG. 1. Such webs suitably have a dryer basisweight of about 9-12 pounds per 2,880 square feet and a stretch at breakin the range of -35 percent. The adhesive supplied to the upper web waspolyvinyl alcohol. Other adhesives may, of course, be employed. Thespiral pattern of the rolls had lands about 0.030 inch wide and extendedcontinuously at a 45 angle with respect to the axis of the roll. Thedepth ofthe ribs and the distance between ribs was about 0.070 inch.Engraving the lands into recesses and projections reduced the land areaof the sheet containing adhesive. from 30 to 9 percent. This reduces theamount of adhesive applied by a factor of over 3 to 1. Resultinglaminated product produced by this method had good bulk characteristics,embossing pattern definition and acceptable ply attachment for toweluse. Ply attachment values of 10 gms. per 4 inches and up were possible,depending on the amount ofadhesive applied and the combining nippressure between the two engraved steel embossing rolls. Ply atouterwebs on a portion of the sample, and then placing those 4-inch wideseparated web portions in an Instron tester to measure the forcerequired for ply separation.

EXAMPLE 2 Two and three-ply towel weight samples were prepared using theabove spiral rib embossing pattern. prior to and after engraving thecross-over points. For the two-ply samples and the outer surface pliesof the three-ply samples, a creped tissue web having a dryer basisweight of 10-1 1 pounds per 2,880 square feet and a stretch at break ofabout 32 percent was employed. For the center web in the three-plysamples, a creped tissue web having a dryer basis weight of about 6-7pounds per 2,880 square feet and a stretch at break of about percent.The following shows test results on these samples.

Engraved C ross- The Handle-O-Meter values show the improved limpnessfor the samples produced when the cross-over points were engraved, whichis the result of reducing the adhesive coverage on a large portion ofthe continuous spiral rib lands.

The Handle-O-Meter values were obtained by using a common Thwing-AlbertHandle-O-Meter test. For test purposes to obtain the Handle-O-Metervalue in the machine direction. 2 /2 inches wide X 6 inches long sampleswere used, and for cross direction samples were 2% inches wide X 3%inches long. The Handle-O- Meter values give an indication of sheetstiffness and lower values indicate better handle and less stiffness.

In most instances the application of adhesive to the extent of about 5percent of the sheet area is suitable if the projections of the rollwhich receive the adhesive are well and uniformly spaced. The patternand basetissue weight chosen for the final product influence the amountof adhesive applied to the sheet. With heavier weight sheets and moregross patterns usually a greater amount of area of the sheet is occupiedby adhesive to insure of good laminate characteristics. The situationsfound particularly useful are those in which 10 to 50 percent of the ribsurface area is constituted by projections for receipt of adhesive.

For a three ply sheet where the projections and recesses alternate onone land of each roll, the same principles are applicable but 5 percentto 25 percent of the rib surface area will be projections but, ofcourse. adhesive is then applied to both outer sheets.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that I do not limit myself to the specific embodimentsthereof except as defined in the appended claims.

1 claim:

1. ln embossing apparatus, a pair of cooperable embossing rolls eachhaving a series of ribs and grooves extending continuously lengthwise ofthe rolls, the ribs being spaced apart circumferentially by the saidgrooves disposed about the roll periphery, the ribs of one roll eachhaving a plurality of surface land areas also extending longitudinallyon the ribs and projections of these ribs extending above the land areasand separated longitudinally by the land areas and peripherally fromprojections of adjacent ribs by the said grooves, the ribs of the otherroll having surface land areas extending longitudinally on the ribs andrecesses of the ribs lying below and separated by these latter mentionedland areas for mating with the said projections, and the projections ofthe one said roll in the rotation of the cooperable embossing rollsbeing receivable in the mating recesses of the other said roll, the saidrecesses being shallow relative to the depth of the ribs. I

2. Embossing apparatus as claimed in claim I in which the land areas ofthe ribs of the one said roll are of greater length along the ribs thanthe projections separated by the land areas and the projections have aheight of about 0.005 inch.

3. Embossing apparatus as claimed in claim 1 in which the projectionsand recesses as viewed in plan are rectangular and the projection andrecess at each end of a rib is triangular.

4. Embossing apparatus as claimed in claim 1 in which the projectionsand recesses are generally conical in shape and each lies wholly withinthe width of the rib which accommodates it.

5. Embossing apparatus as claimed in claim 1 in which each of the ribsof each roll have projections, recesses and land areas, the land areasof each roll separating the projections and recesses of that roll andthe projections of each roll being receivable in the recesses of theother.

1. In embossing apparatus, a pair of cooperable embossing rolls eachhaving a series of ribs and grooves extending continuously lengthwise ofthe rolls, the ribs being spaced apart circumferentially by the saidgrooves disposed about the roll periphery, the ribs of one roll eachhaving a plurality of surface land areas also extending longitudinallyon the ribs and projections of these ribs extending above the land areasand separated longitudinally by the land areas and peripherally fromprojections of adjacent ribs by the said grooves, the ribs of the otherroll having surface land areas extending longitudinally on the ribs andrecesses of the ribs lying below and separated by these latter mentionedland areas for mating with the said projections, and the projections ofthe one said roll in the rotation of the cooperable embossing rollsbeing receivable in the mating recesses of the other said roll, the saidrecesses being shallow relative to the depth of the ribs.
 2. Embossingapparatus as claimed in claim 1 in which the land areas of the ribs ofthe one said roll are of greater length along the ribs than theprojections separated by the land areas and the projections have aheight of about 0.005 inch.
 3. Embossing apparatus as claimed in claim 1in which the projections and recesses as viewed in plan are rectangularand the projection and recess at each end of a rib is triangular. 4.Embossing apparatus as claimed in claim 1 in which the projections andrecesses are generally conical in shape and each lies wholly within thewidth of the rib which accommodates it.
 5. Embossing apparatus asclaimed in claim 1 in which each of the ribs of each roll haveprojections, recesses and land areas, the land arEas of each rollseparating the projections and recesses of that roll and the projectionsof each roll being receivable in the recesses of the other.